Oil and gas wells can be drilled more efficiently and economically if downtime is minimized and hole and drill string problems are eliminated.
Drilling fluids or muds are commonly used in the drilling of oil and gas wells provide numerous functions including: (1) cooling the drill bit; (2) lubricating the drill string; (3) cleaning the bore hole; (4) bringing the cuttings to the surface; (5) preventing the cavings of the formations by providing hole stability; (6) controlling fluid loss into the formations; and (7) exerting pressure to the sides of the bore hole to prevent the entrance of liquids or gases into the bore hole from the formation being penetrated.
The drilling fluid additive must have a low fluid loss to prevent excessive loss of fluid into the formation by depositing an impervious filter cake on the sides of the bore hole. The thickness of the filter cake is usually directly proportional to the volume of fluid loss. Therefore, the lower the fluid loss, the thinner the filter cake. Maintaining the diameter of the bore hole being drilled is critical to a successful operation. If the fluid loss is high, then the wall cake will be thick and therefore increasing the chance of sticking of the drill string.
Fluid loss additives most commonly used to control the fluid loss and also the wall cake thickness are bentonite clays, polymers, lignites, and surfactants.
Marine or fish oil is a versatile product and finds many applications in the food, feed and technical industries of the world. Like other fats and oils, fish oils consist of a mixture of triglycerides of various long-chain fatty acids with small amounts of mono- and diglycerides, free fatty acids and sterols. The fatty acids that characterize fish oils are similar to those in various vegetable oils and animal fats differing principally in their high proportions of long-chain polyunsaturated fatty acids with five and six double bonds. Marine oils differ among themselves in the percentage of fatty acids.
Although the use of fish oil in drilling/completion fluids has been contemplated, there have been no teachings of how fish oils can be incorporated into drilling fluid with improved results. An article entitled "How about fish oil in your mud"? by Robert Garrett was published in Drilling & Completion Fluids, November 1993 and discussed the need for biodegradable, low-toxicity and earth-friendly materials. However, the article did not discuss how fish oils could be implemented into a drilling fluid.